gonzui

    1: /* e_sinhf.c -- float version of e_sinh.c.
    2:  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
    3:  */
    4: 
    5: /*
    6:  * ====================================================
    7:  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
    8:  *
    9:  * Developed at SunPro, a Sun Microsystems, Inc. business.
   10:  * Permission to use, copy, modify, and distribute this
   11:  * software is freely granted, provided that this notice 
   12:  * is preserved.
   13:  * ====================================================
   14:  */
   15: 
   16: #include "math.h"
   17: #include "math_private.h"
   18: 
   19: static const float one = 1.0, shuge = 1.0e37;
   20: 
   21: float
   22: sinhf(float x)
   23: {       
   24:         float t,w,h;
   25:         int32_t ix,jx;
   26: 
   27:         GET_FLOAT_WORD(jx,x);
   28:         ix = jx&0x7fffffff;
   29: 
   30:     /* x is INF or NaN */
   31:         if(ix>=0x7f800000) return x+x; 
   32: 
   33:         h = 0.5;
   34:         if (jx<0) h = -h;
   35:     /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
   36:         if (ix < 0x41b00000) {         /* |x|<22 */
   37:             if (ix<0x31800000)                 /* |x|<2**-28 */
   38:                 if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
   39:             t = expm1f(fabsf(x));
   40:             if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
   41:             return h*(t+t/(t+one));
   42:         }
   43: 
   44:     /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
   45:         if (ix < 0x42b17180)  return h*expf(fabsf(x));
   46: 
   47:     /* |x| in [log(maxdouble), overflowthresold] */
   48:         if (ix<=0x42b2d4fc) {
   49:             w = expf((float)0.5*fabsf(x));
   50:             t = h*w;
   51:             return t*w;
   52:         }
   53: 
   54:     /* |x| > overflowthresold, sinh(x) overflow */
   55:         return x*shuge;
   56: }